Spring chuck devices of this sort represent a quick and secure connection to e.g. gas bottles because of their easy handling, by means of which a time-consuming screwing off and on of the fitting is not required. The spring chucks engage thereby in an interlocking manner to the interior and exterior threads, to collar-, muff- and flange-connections etc.
A plug-in coupling for a pressure sealed connection to a device which has a complementary connection is described in EP 0 202 592. This plug-in coupling comprises a cylindrical housing with a piston which can be adjusted within it in an a axial direction and which has spring chucks projecting from the housing on one of its ends. When the piston is adjusted in an axial direction relative to the housing, the spring chucks are expanded radially or pressed together via a ramp or diagonal surface arrangement between the housing and the piston according to the direction of movement. In a first embodiment form the piston and the spring chucks are designed in one piece. This demands a thin transition area between the piston and the spring chucks for the spring chucks to be able to be slid inwards or outwards via the ramp arrangement in a resilient manner. Even with larger sizes of device, this transition must be relatively thin so that the force needed for adjustment does not become too great. With frequent load changes, however, this thin transition is particularly prone to fatigue fracture. In addition, in order to replace the spring chucks, the entire plug-in coupling construction must be dismantled.
The disadvantages of the integral embodiment form are compensated for a by a further embodiment form in EP 0 202 592, in which the spring chucks and the piston constitute separate components and the spring chucks are hooked onto the piston. The spring chucks and the tension piston can be pinned together also for additional security. As a result the spring chucks can be replaced without changing the tension piston and can be fitted individually to the respective counter connection. However, in this embodiment form at least the front portion of the housing must be dismantled also, e.g. unscrewed for the spring chucks to be replaced.